London, Dartmoor, The Great Grimpen Mire
The Hound of the Baskervilles gives us the impression that the city of London is basically sitting in the palm of Sherlock Holmes' hand. In London, Holmes has Cartwright, the admiring messenger kid who runs errands for him. He's got art galleries and operas, insider connections with Scotland Yard, and his loyal pal Watson. He's a local celeb.
In fact, when Holmes reflects back on Stapleton's plans, he notes that Stapleton decides to leave London to continue his plot against Sir Henry in Dartmoor because Stapleton "understood that [Holmes] had taken over the case in London, and that therefore there was no chance for him there" (15.16). Holmes is so influential in London that he actually scares Stapleton away just by starting to look into Sir Henry's case there.
But Dartmoor is totally different from Holmes' London: it's gloomier and more isolated. Between the moaning howls of the Hound, the prehistoric settlements (which really do exist), and the close proximity of the famous prison, Dartmoor seems like an excellent setting for a Gothic horror novel. How can Holmes possibly apply his usual methods of logic and deduction in such a wild, lonely, unpredictable place?
Being Holmes, he manages very well. When Watson first sets eyes on him just outside of the prehistoric hut that Holmes has been camping in, Watson finds that Holmes "had contrived, with that cat-like love of personal cleanliness which was one of his characteristics, that his chin should be as smooth and his linen as perfect as if he were in Baker Street" (12.4).
London is the modern, progressive city of the future where reason prevails and the lights stay on. In contrast, Dartmoor and its surrounding countryside represent the darkness and superstition of the ancient past. Holmes, in from London, manages to "illuminate" the dark and sinister goings-on in Dartmoor. Much more on this in our "Themes" section.